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41.
The acidity function of solutions of methanesulfonic acid (MSA) in ethyl acetate (EA) was measured by the indicator method at 25 °C in the 0.4—100% concentration range. Molecular complexes formed by MSA and EA show a higher ionizing activity than H5O2
+ ions. The relative ionizing activity of the MSA·EA complexes and ion pairs formed by MSA and DMF was determined. 相似文献
42.
Pawe Mateusz Nowak Maria Klag Gabriela Kzka Magorzata Gob Micha Wo
niakiewicz 《Molecules (Basel, Switzerland)》2022,27(15)
This article presents the first successful application of a capillary electrophoresis-microscale thermophoresis tandem technique (CE-MST) for determining the values of equilibrium constant, realized by connecting online the CE and MST instruments using a fused-silica capillary. The acid-base dissociation of fluorescein isothiocyanate, expressed by the acidity constant value (pKa), was used as a model. The measurement procedure consisted of introducing a mixture containing the analyte and a deliberately added interferent into the CE capillary, electrophoretic separation of the analyte from the interferent, the detection of the analyte with a CE-integrated detector, detection with a MST detector, and then stopping the flow temporarily by turning off the voltage source to conduct the thermophoretic measurement. The analysis of migration times, peak areas and MST responses obtained concurrently for the same sample allowed us to determine the pKa value using three independent methods integrated within one instrumentation. The analyte was effectively separated from the interferent, and the acidity values turned out to be consistent with each other. An attempt was also made to replace the standard commercial CE instrument with a home-made portable CE setup. As a result, the similar pKa value was obtained, at the same time proving the possibility of increasing cost efficiency and reducing energy consumption. Overall, the CE-MST technique has a number of limitations, but its unique analytical capabilities may be beneficial for some applications, especially when sample separation is needed prior to the thermophoretic measurement. 相似文献
43.
利用工业上应用广泛的铝阳极氧化电解实验及其着色工艺,阐述该实验原理及着色机理,用食用色素对阳极氧化后的铝片着色,得到色彩丰富的铝片,并制备出一种可以检验气体酸碱性的简易气体酸碱性检测器。该实验可以用于拓展课堂的实验教学,简便易行、原料易得、成本低、趣味性强。 相似文献
44.
M. S. Shvartsberg A. V. Piskunov M. A. Mzhel'skaya A. A. Moroz 《Russian Chemical Bulletin》1993,42(8):1357-1363
A general method for the synthesis of substituted fused polycyclic compounds containing a 4-alkylamino or 4-dialkylaminopyridine cycle has been proposed. The method includes the addition of primary or secondary amines to vicinal (acylethynyl)arylamines followed by the cyclization of the adducts under acidic or basic catalysis conditions. Various aminonaphthoquinolinediones and aminoquinolines have been prepared in high yields by this method.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1423–1429, August, 1993. 相似文献
45.
M. I. Kabachnik S. V. Matveev V. D. Bazilyanskaya L. P. Loginova Yu. M. Polikarpov 《Russian Chemical Bulletin》1993,42(7):1218-1221
A novel polydentate phosphorus-containing complexing agent,cis,cis-1,3,5-tri[2-(diphenyl-phosphinyl)ethylamino]cyclohexane, has been prepared on the basis ofcis,cis-1,3,5-triamino-cyclohexane. The method of potentiometric titration in an aqueous—organic medium (70% ethanol, ionic strength 0.01M LiNO3, 298 K) has been used to study the acid-base and complexing properties of the title compound. The ligand thus prepared forms 11 complexes with Cu2+, Co2+, Zn2+, and Ni2+ cations; formation of hydroxocomplexes MOHL+ has been observed in the case of Zn2+ and Cd2+.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1276–1279, July, 1993.The authors are grateful to A. G. Matveeva for his assistante in discussing the results of this study and in preparing this paper. 相似文献
46.
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48.
Giuseppe Arena Raffaele P. Bonomo Annalinda Contino Fabio G. Gulino Antonio Magrì Domenico Sciotto 《Journal of inclusion phenomena and macrocyclic chemistry》1997,29(3-4):347-363
A new water soluble receptor 5,11,17,23-tetrasulphonato-25,27-di(hydroxycarbonylmethoxy)-26,28-dihydroxycalix[4]arene was synthesized andcharacterized and its proton and copper(II) complexes were studied andcompared with the analogous species of the fully carboxylated ligand5,11,17,23-tetrasulphonato-25,26,27,28-tetrakis(hydroxycarbonylmethoxy)calix[4]arene. H° and S° values are crucial for understanding thepeculiar acid-base properties of the ligand. EPR spectra together with theUV-VIS spectral data reveal the coordination stereochemistry of thecopper(II) species. 相似文献
49.
Shingo Katayama Keiji Iwata Yuji Kubo Noriko Yamada 《Journal of Sol-Gel Science and Technology》2003,26(1-3):397-401
Solid acid-base properties of methylsiloxane-based inorganic/organic hybrids were controlled by incorporation of inorganic components other than Si into methylsiloxane networks. The effect of different inorganic components on the solid acid-base properties was estimated by first-principles calculations based on density functional theory (DFT). The deprotonation tends to occur in the order Si < Al < Nb inorganic components, suggesting that the acidity increases in the same order. Methylsiloxane-based hybrids with solid acid-base properties were also synthesized by incorporating inorganic components derived from metal alkoxides. Hammett indicators revealed that the solid acidity increased in the order Si < Al < Nb inorganic components, which was consistent with the results of first-principles calculations. Preliminary experiments revealed that the methylsiloxane-based hybrids also provided a solid basic nature by containing Ca and Y inorganic components derived from metal alkoxides. The acidic hybrids were found to have Brønsted acid sites from the FT-IR experiments of adsorbed pyridine on the hybrids. 相似文献
50.
Shingo Katayama Noriko Yamada Masanobu Awano 《Journal of Sol-Gel Science and Technology》2004,32(1-3):311-316
The preparation and NO-adsorption/desorption behavior of Li, Ca and Ba silicates were investigated aiming at the application to a NOx-absorbent. Li silicate was prepared by reaction of HSi(OC2H5)3 with aqueous lithium silicate solution (LSS). Ca and Ba silicates were prepared from gels obtained using CH3Si(OC2H5)3, Si(OC2H5)4, HSi(OC2H5)3 and alkaline-earth alkoxides. The surface of these silicates indicated the solid basicity of H0 = 9 and adsorbed the acidic gas of NO. FT-IR spectra of the silicates adsorbing NO showed the absorption peaks in the range of 1300–1600 cm– 1 corresponding to ionic and covalent nitrate NO3–. The complete desorption of adsorbed NO species occurred above 500°C in the Li silicate, above 500°C in the Ca and Ba silicates prepared using CH3Si(OC2H5)3, and above 700°C in the Ba and Ca silicates prepared using Si(OC2H5)4. Regarding the Ca and Ba silicates, the difference in siloxane structure is thought to cause the difference in adsorption state and desorption behavior of NO. 相似文献